U.S. patent number 10,735,328 [Application Number 15/502,245] was granted by the patent office on 2020-08-04 for information communication system, information communication method and device.
This patent grant is currently assigned to NEC CORPORATION. The grantee listed for this patent is NEC Corporation. Invention is credited to Takao Ochi, Akio Tajima, Ken-ichiro Yoshino.
United States Patent |
10,735,328 |
Ochi , et al. |
August 4, 2020 |
Information communication system, information communication method
and device
Abstract
In order to achieve the dispersion of a processing load between
communication devices that perform information transmission, an
information communication system according to an exemplary aspect
of the present invention includes a first transmission system
configured to transmit information in a direction from a first
communication device to a second communication device; and a second
transmission system configured to transmit information in a
direction opposite to the direction of the first transmission
system, wherein part of transmission information is received as
received information in each of the first transmission system and
the second transmission system.
Inventors: |
Ochi; Takao (Tokyo,
JP), Yoshino; Ken-ichiro (Tokyo, JP),
Tajima; Akio (Tokyo, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
NEC Corporation |
Minato-ku, Tokyo |
N/A |
JP |
|
|
Assignee: |
NEC CORPORATION (Tokyo,
JP)
|
Family
ID: |
1000004967153 |
Appl.
No.: |
15/502,245 |
Filed: |
August 20, 2015 |
PCT
Filed: |
August 20, 2015 |
PCT No.: |
PCT/JP2015/004158 |
371(c)(1),(2),(4) Date: |
February 07, 2017 |
PCT
Pub. No.: |
WO2016/031194 |
PCT
Pub. Date: |
March 03, 2016 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20170237666 A1 |
Aug 17, 2017 |
|
Foreign Application Priority Data
|
|
|
|
|
Aug 25, 2014 [JP] |
|
|
2014-170087 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04L
9/08 (20130101); H04L 9/0869 (20130101); H04L
9/12 (20130101); H04L 9/0852 (20130101); H04L
47/125 (20130101); H04L 47/54 (20130101); H04L
9/0858 (20130101) |
Current International
Class: |
H04L
12/803 (20130101); H04L 9/08 (20060101); H04L
9/12 (20060101); H04L 12/863 (20130101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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102055584 |
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May 2011 |
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CN |
|
103326850 |
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Sep 2013 |
|
CN |
|
103477581 |
|
Dec 2013 |
|
CN |
|
103618597 |
|
Mar 2014 |
|
CN |
|
1054524 |
|
Nov 2000 |
|
EP |
|
1 755 269 |
|
Oct 2014 |
|
EP |
|
H09-238132 |
|
Sep 1997 |
|
JP |
|
2000-332655 |
|
Nov 2000 |
|
JP |
|
2011-082832 |
|
Apr 2011 |
|
JP |
|
2012-147078 |
|
Aug 2012 |
|
JP |
|
Other References
Communication dated Mar. 21, 2018 from the European Patent Office
in counterpart application No. 15837039.5. cited by applicant .
Hughes et al., "Quantum key distribution over a 48km optical fibre
network", Journal of Modern Optics, vol. 47, No. 2/3, 2000, pp.
533-547. (16 pages total). cited by applicant .
Brodsky et al., "Effect of a Weak Magnetic Field on Quantum
Cryptography Links", ECOC 2005 Proceedings, vol. 6, Sep. 25, 2005,
pp. 19-20. cited by applicant .
Charles H. Bennett et al. "Quantum Cryptography: Public Key
Distribution and Coin Tossing" IEEE Int. Conf. on Computers,
Systems, and Signal Processing, Bangalore, India, Dec. 10-12, 1984.
cited by applicant .
International Search Report for PCT Application No.
PCT/JP2015/004158, dated Sep. 29, 2015. cited by applicant .
English translation of Written opinion for PCT Application No.
PCT/JP2015/004158. cited by applicant .
Chinese Office Action for CN Application No. 201580045957.0 dated
Jul. 2, 2019 with English Translation. cited by applicant.
|
Primary Examiner: Sheikh; Ayaz R
Assistant Examiner: Aga; Sori A
Claims
What is claimed is:
1. An information communication system, comprising: a first
transmission system configured to transmit information in a
direction from a first communication device to a second
communication device; and a second transmission system configured
to transmit information in a direction opposite to the direction of
the first transmission system, wherein each of the first
communication device and the second communication device includes
an information processor configured to perform information
processing using transmission information transmitted from its own
device and received information received from another communication
device, and a data volume of the received information is smaller
than a data volume of the transmission information, wherein each of
the first communication device and the second communication device
includes a transmitter configured to transmit transmission
information to another communication device, a receiver configured
to receive received information from the another communication
device, a switch configured to, at a time of parameter adjustment
of the transmitter, turn back a transmission signal outputted from
the transmitter and make the transmission signal be inputted to the
receiver, and a parameter adjustment unit configured to adjust a
transmission parameter of the transmitter based on a received
signal of the receiver having received the signal that is turned
back.
2. A communication device, comprising: a transmitting unit
configured to transmit information to another communication device
through a first transmission line; a receiving unit configured to
receive information through a second transmission line from the
another communication device; an information processor configured
to perform information processing using the transmission
information transmitted by the transmitting unit and the received
information received from the another communication device, wherein
a data volume of the received information is smaller than a data
volume of the transmission information; a switch configured to, at
a time of parameter adjustment of the transmitting unit, turn back
a transmission signal outputted from the transmitting unit and make
the transmission signal be inputted to the receiving unit; and a
parameter adjustment unit configured to adjust a transmission
parameter of the transmitting unit based on a received signal of
the receiving unit having received the signal that is turned
back.
3. An information communication method, comprising: transmitting
and receiving information at each of a first communication device
and a second communication device by use of a first transmission
system and a second transmission system, the first transmission
system and the second transmission system having transmission
directions opposite to each other; receiving part of transmission
information as received information in each of the first
transmission system and the second transmission system; performing,
at each of the first communication device and the second
communication device, information processing using transmission
information transmitted from its own device and received
information received from another communication device, wherein a
data volume of the received information is smaller than a data
volume of the transmission information; turning back, at a time of
parameter adjustment of a transmitter to transmit transmission
information to another communication device, in each of the first
communication device and the second communication device, a
transmission signal outputted from the transmitter and making the
transmission signal be inputted to a receiver to receive received
information from the another communication device; and adjusting a
transmission parameter of the transmitter based on a received
signal of the receiver having received the signal that is turned
back.
4. The information communication system according to claim 1,
wherein the first transmission system is configured to transmit
first random number information in a direction from the first
communication device to the second communication device; and the
second transmission system is configured to transmit second random
number information in a direction opposite to the direction of the
first transmission system, wherein in each of the first
transmission system and the second transmission system, part of
transmission random number information transmitted is received as
received random number information.
5. The information communication system according to claim 4,
wherein each of the first communication device and the second
communication device includes an encryption key generation unit
configured to generate an encryption key using the transmission
random number information transmitted by its own device and the
received random number information received from another
communication device.
6. The information communication system according to claim 4,
wherein each of the first communication device and the second
communication device includes a transmitter configured to transmit
transmitting random number information to another communication
device, a receiver configured to receive received random number
information from the another communication device, a switch
configured to, at a time of parameter adjustment of the
transmitter, turn back a transmission signal outputted from the
transmitter and make the transmission signal be input to the
receiver, and a parameter adjustment unit configured to adjust a
transmission parameter of the transmitter based on a received
signal of the receiver having received the signal that is turned
back.
7. The information communication system according to claim 5,
wherein each of the first communication device and the second
communication device includes a transmitter configured to transmit
transmitting random number information to another communication
device, a receiver configured to receive received random number
information from the another communication device, a switch
configured to, at a time of parameter adjustment of the
transmitter, turn back a transmission signal outputted from the
transmitter and make the transmission signal be input to the
receiver, and a parameter adjustment unit configured to adjust a
transmission parameter of the transmitter based on a received
signal of the receiver having received the signal that is turned
back.
Description
This application is a National Stage Entry of PCT/JP2015/004158
filed on Aug. 20, 2015, which claims priority from Japanese Patent
Application 2014-170087 filed on Aug. 25, 2014, the contents of all
of which are incorporated herein by reference, in their
entirety.
TECHNICAL FIELD
The present invention relates to an information communication
system, an information communication method and device to transmit
and receive information between communication devices.
BACKGROUND ART
In a data transmission between communication devices, not all of
information transmitted from a transmission side is received at a
receiving end. For example, it is known that a packet loss occurs
due to a load state or the like of a network, and, in addition,
there is a communication system in which only a part of transmitted
data reaches to the receiver as characteristics of a transmission
system including a transmitter, a receiver, and a channel that
connects them. As an example of such communication system, a
quantum key distribution (QKD) system will be described
briefly.
It is necessary to share a shared key required for encryption and
decryption of information between a transmission end and a
receiving end as secret information, and QKD technology is regarded
to be promising as a technology to generate and share such secret
information. According to the QKD technology, contrary to a
conventional optical communication, it is possible to generate and
share a common key between a transmitter and a receiver by
transmitting a random number with the number of photons per bit
equal to one or less. The QKD technology has the security that is
based on the principle of quantum mechanics that a photon observed
once cannot be completely returned to the quantum state before the
observation, not the security that is based on conventional
computational complexity.
It is necessary in the QKD technology to carry out several steps
before an encryption key used for cryptographic communication is
generated. Hereinafter, a generation process of a typical
encryption key will be described with reference to FIG. 1.
As shown in FIG. 1, in a single photon transmission, a random
number is transmitted through a quantum channel by a weak optical
pulse train with the number of photons per bit equal to one or
less, as mentioned above. As the QKD method, a BB84 method using
four quantum states is widely known (Non Patent Literature 1), for
example. When a transmitter transmits an original random number by
a single photon transmission, most of it is lost due to the loss or
the like of a transmission line; and bits that can be received by a
receiver become a very small part of the transmitted bits, which is
called a raw key. For example, the data volume that can be received
by a receiver is about 1/1000 of the transmitted data volume.
Subsequently, a basis reconciliation, error correction, and privacy
amplification processing are performed on the raw key that is
received with most of the transmitted random numbers having been
lost due to the quantum channel transmission, using a communication
channel with normal optical intensity (classical channel). In each
step of the basis reconciliation, error correction and, privacy
amplification processing, a bit elimination is carried out to
eliminate bits disclosed to the other side and the possibility of
wiretapping. Thus, in a transmission system in which most of
transmitting data is lost in a transmission channel, and data
elimination is performed in subsequent processes, a received data
volume finally obtained becomes very small compared with the
transmitted data volume.
CITATION LIST
Non Patent Literature
[NPL 1] "QUANTUM CRYPTOGRAPHY, PUBLIC KEY DISTRIBUTION AND COIN
TOSSING" IEEE Int. Conf. on Computers, Systems, and Signal
Processing, Bangalore, India, Dec. 10-12, 1984, pp. 175-179,
Bennett, Brassard
SUMMARY OF INVENTION
Technical Problem
As mentioned above, in a transmission system in which most of
transmitting data is lost, a problem newly arises that the
processing efficiency declines because large unbalance occurs with
respect to a data volume to be processed between a transmission end
to process transmitting data and a receiving end to process
received data, and because the processing load of the transmitting
end becomes larger.
The object of the present invention is to provide an information
communication system, an information communication method and
device that can achieve the dispersion of a processing load between
communication devices that perform information transmission.
Solution to Problem
An information communication system according to an exemplary
aspect of the present invention, an information communication
system to transmit and receive information between communication
devices, includes a first transmission system configured to
transmit information in a direction from a first communication
device to a second communication device; and a second transmission
system configured to transmit information in a direction opposite
to the direction of the first transmission system, wherein part of
transmission information is received as received information in
each of the first transmission system and the second transmission
system.
A communication device according to an exemplary aspect of the
present invention, a communication device to transmit and receive
information to and from another communication device, includes a
transmitting means for transmitting information to the another
communication device through a first transmission line; and a
receiving means for receiving information through a second
transmission line from the another communication device, wherein
part of transmission information is received as received
information in each of the first transmission line and the second
transmission line.
An information communication method according to an exemplary
aspect of the present invention, an information communication
method to transmit and receive information between the
communication devices, includes transmitting and receiving
information at each of a first communication device and a second
communication device by use of a first transmission system and a
second transmission system, the first transmission system and the
second transmission system having transmission directions opposite
to each other; and receiving part of transmission information as
received information in each of the first transmission system and
the second transmission system.
Advantageous Effects of Invention
According to the present invention, it becomes possible to disperse
a processing load between communication devices.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a schematic diagram to illustrate information-processing
steps in a quantum key distribution (QKD) system.
FIG. 2 is a block diagram illustrating a schematic configuration of
an information communication system in accordance with a first
example embodiment of the present invention.
FIG. 3 is a block diagram illustrating a configuration example of
an information communication system in accordance with a second
example embodiment of the present invention.
FIG. 4 is a block diagram illustrating a configuration example of
an information communication system in accordance with a third
example embodiment of the present invention.
EXAMPLE EMBODIMENT
The Outline of Example Embodiments
According to the example embodiments of the present invention, when
part of transmission information is received as received
information in a transmission system set between communication
devices, it becomes possible to disperse a processing load between
the communication devices by providing a pair of transmission
systems with the transmission directions opposite to each other. In
each communication device, if a predetermined processing using
transmission information and a predetermined processing using
receiving information are performed, the equalization of the
processing loads can be achieved between the communication devices,
and sufficient information generation efficiency can be obtained.
Because both of the transmitter and the receiver are provided in
each communication device, transmit data can be received by a
receiver in the own device, and it becomes possible to adjust
parameters of a transmitter in each communication device. Example
embodiments of the present invention will be described below in
detail using figures. The direction of the arrow in the figures
indicates a direction as an example and does not limit the
direction of the signals between the blocks.
1. The First Example Embodiment
As illustrated in FIG. 2, in an information communication system
according to the first example embodiment of the present invention,
a first communication device 10 and a second communication device
20 perform information transmission in the directions opposite to
each other by a first transmission system 31 and a second
transmission system 32. The first transmission system 31 performs
one direction transmission from the first communication device 10
to the second communication device 20, and includes a transmitter
101 of the first communication device 10, a receiver 201 of the
second communication device 20, and a first transmission line 33
connecting the transmitter 101 and the receiver 201. The second
transmission system 32 performs one direction transmission in the
direction opposite to that of the first transmission system 31, and
includes a receiver 102 of the first communication device 10, a
transmitter 202 of the second communication device 20, and a second
transmission line 34 connecting the transmitter 202 and the
receiver 102.
The first communication device 10 includes the transmitter 101, the
receiver 102 and a data processor 103. The data processor 103
receives inputs of transmission information TD1 on the transmitter
101 and received information RD2 from the second communication
device 20 that is received by the receiver 102, and performs
predetermined data processing on the information respectively. The
second communication device 20 includes the receiver 201, the
transmitter 202 and, a data processor 203. The data processor 203
receives inputs of transmission information TD2 on the transmitter
202 and received information RD1 from the first communication
device 10 that is received by the receiver 201, and performs
predetermined data processing on the information respectively. The
data processor 103 of the first communication device 10 and the
data processor 203 of the second communication device 20 can
perform an identical information processing and generate a similar
sort of information, for example.
The first transmission system 31 transmits the information in the
direction from the first communication device 10 to the second
communication device 20, and has the characteristics that a
received information volume becomes less than a transmission
information volume. That is to say, the transmission information
TD1 transmitted from the transmitter 101 is partially lost in the
first transmission line 33 and/or the receiver 201, and only part
of the transmission information TD1 is received by the receiver 201
as the received information RD1.
The second transmission system 32 transmits the information in the
direction from the second communication device 20 to the first
communication device 10 contrary to the first transmission system
31, and has the characteristics that a received information volume
becomes less than a transmission information volume, as is the case
with the first transmission system 31. That is to say, the
transmission information TD2 transmitted from the transmitter 202
is transmitted through the second transmission line 34 and is
received by the receiver 102. On this occasion, the transmission
information TD2 is partially lost in the second transmission line
34 and/or the receiver 102, and only part of the transmission
information TD2 is received by the receiver 102 as the received
information RD2.
Consequently, the data processor 103 receives inputs of the
transmission information TD1 having a large data volume and the
received information RD2 having a relatively small data volume and
performs processing, and similarly, the data processor 203 receives
inputs of the transmission information TD2 having a large data
volume and the received information RD1 having a relatively small
data volume and performs processing. If the first transmission
system 31 and 32 have similar transmission characteristics, and the
data processors 103 and 203 perform identical information
processing, it becomes possible to reduce the unbalance of loads
regarding the data processing between the first communication
device 10 and the second communication device 20.
As mentioned above, according to the present example embodiment, it
becomes possible to disperse the processing loads between the
communication devices by setting a pair of transmission systems 31
and 32 each of which transmits in a direction opposite to each
other. That is to say, the processing capacity can be utilized
efficiently because the processing load can be equalized between
the communication devices. It becomes possible to generate
efficiently desired information because each communication device
can generate the information by processing both of the transmission
information and the received information.
2. The Second Example Embodiment
As illustrated in FIG. 3, an information communication system
according to the second example embodiment of the present invention
is a system in which the first example embodiment mentioned above
is applied to a QKD system.
In FIG. 3, a communication device A and a communication device B
transmit a single photon pulse train modulated by random number
information in the directions opposite to each other using a
quantum channel transmission system Q1 and a quantum channel
transmission system Q2. The quantum channel transmission system Q1
includes a transmitter 301 of the communication device A, a
receiver 401 of the communication device B, a transmission line
(quantum channel) connecting the transmitter 301 and the receiver
401. The quantum channel transmission system Q2 includes a
transmitter 402 of the communication device B, a receiver 302 of
the communication device A, and a transmission line (quantum
channel) connecting the transmitter 402 and the receiver 302. In
the present example embodiment, respective transmission lines of
the quantum channel transmission systems Q1 and Q2 may be composed
of optical fibers that physically differ from each other or may be
wavelength-multiplexed in an identical optical fiber.
The communication device A and the communication device B perform
optical communication with the optical power having a normal level
using a classical channel transmission system C. The classical
channel transmission system C includes an optical communication
unit 304 of the communication device A, an optical communication
unit 404 of the communication device B, and a transmission line
(classical channel) connecting the optical communication unit 304
and the optical communication unit 404. The communication device A
and the communication device B perform, in addition to the
synchronous processing, the basis reconciliation with the other
communication device, the error correction, and the privacy
amplification processing, as mentioned above, using the classical
channel transmission system C. A classical channel in the classical
channel transmission system C may be provided by wavelength
multiplexing in the same optical fiber as that including the
quantum channel transmission systems Q1 and Q2. Alternatively, a
synchronization channel for the synchronous processing can be
provided in another optical fiber.
The classical channel of the classical channel transmission system
C may be an electric communication path by an electric signal, not
an optical communication. In this case, it is only necessary to
replace the optical communication units 304 and 404 with
communication units that transmit and receive an electric
signal.
The communication device A includes the transmitter 301, the
receiver 302, an encryption key generation unit 303, the optical
communication unit 304, and a control unit 305. The encryption key
generation unit 303 corresponds to the data processor 103 in the
first example embodiment. The encryption key generation unit 303
receives inputs of transmission information (original random
number) TD1 on the transmitter 301 and received information RD2
received by the receiver 302 from the communication device B. Then,
the encryption key generation unit 303 generates an encryption key
by performing the basis reconciliation with the communication
device B through the optical communication unit 304, the error
correction, and the privacy amplification processing, as mentioned
above. The control unit 305 controls the overall operations of the
communication device A.
The basic configuration of the communication device B is similar to
that of the communication device A. That is to say, the
communication device B includes the receiver 401, the transmitter
402, an encryption key generation unit 403, the optical
communication unit 404, and a control unit 405. The encryption key
generation unit 403 corresponds to the data processor 203 in the
first example embodiment. The encryption key generation unit 403
receives inputs of transmission information (original random
number) TD2 on the transmitter 402 and received information RD1
received by the receiver 401 from the communication device A. Then,
the encryption key generation unit 403 generates an encryption key
by performing the basis reconciliation with the communication
device A through the optical communication unit 404, the error
correction, and the privacy amplification processing, as mentioned
above. The control unit 405 controls the overall operations of the
communication device B.
In the quantum channel transmission system Q1, the transmitter 301
of the communication device A puts the transmission information
(original random number bit information) TD1 on a very weak optical
pulse train with the number of photons per bit equal to one or
less, and transmits it to the receiver 401 of the communication
device B through a quantum channel. The weak optical pulse train in
transmission is lost in the middle of the transmission line, and
only part of it reaches the receiver 401. The receiver 401 outputs
detected data to the encryption key generation unit 403 as received
information RD1. As mentioned above, the information volume of the
received information RD1 gets down to about 1/1000 of the
information volume of the transmission information TD1, for
example.
In the quantum channel transmission system Q2, the transmitter 402
of the communication device B puts the transmission information
(original random number bit information) TD2 on a very weak optical
pulse train with the number of photons per bit equal to one or
less, and transmits it to the receiver 302 of the communication
device A through a quantum channel. In this case, its transmission
direction is opposite to that of the quantum channel transmission
system Q1. The weak optical pulse train in transmission is lost in
the middle of the transmission line, and only part of it reaches
the receiver 302. The receiver 302 outputs detected data to the
encryption key generation unit 303 as received information RD2. It
is assumed that the information volume of the received information
RD2 also gets down to the same level (about 1/1000) of the
information volume of the transmission information TD2 as is the
case with the quantum channel transmission system Q1.
The encryption key generation unit 303 receives inputs of the
transmission information TD1 having a large data volume and the
received information RD2 having a quite small data volume. The
encryption key generation unit 303 can generate a first encryption
key by performing the basis reconciliation, the error correction,
and the privacy amplification processing, on the transmission
information TD1 and the received information RD1 in the other
communication device B through the classical channel transmission
system C. Similarly, the encryption key generation unit 403 also
receives inputs of the transmission information TD2 having a large
data volume and the received information RD1 having a quite small
data volume. The encryption key generation unit 403 can generate a
second encryption key by performing the basis reconciliation, the
error correction, and the privacy amplification processing, on the
transmission information TD2 and the received information RD2 in
the other communication device A through the classical channel
transmission system C. Because information volume attenuation
arises equally in each of a pair of quantum channel transmission
systems Q1 and Q2 having transmission directions opposite to each
other, the same level of information volume is processed;
consequently, the equalization of processing loads can be achieved
between the encryption key generation units 303 and 403.
3. The Third Example Embodiment
An information communication system according to the third example
embodiment of the present invention is a system obtained by adding
a self-diagnostic function to each communication device according
to the above-mentioned second example embodiment. Specifically, a
transmission parameter adjusting function, and an optical route
switching function of changing the route of transmission light so
as to input the transmission light into the receiver in the own
device at a time of parameter adjustment mode, are added.
Generally, in order to adjust a parameter such as transmission
optical intensity of a transmitter that transmits the
above-mentioned weak optical pulse, a receiver to receive the weak
optical pulse is required. Since weak light is very weak light with
one photon or less per bit, a detector that can detect a single
photon is required; consequently, an avalanche photodiode is
usually used. Accordingly, the parameter adjustment is performed
using a receiver in the other communication device.
However, there is likely to be a wire-tapper on the transmission
path, and there is the threat of damaging the security of QKD if a
wire-tapper intervenes during the parameter adjustment. In
addition, since a single photon detector is very expensive, it is
not rational to install the receiver only for the parameter
adjustment.
According to the present example embodiment, each communication
device has a transmitter and a receiver for a quantum channel
because a pair of quantum channel transmission systems Q1 and Q2
for transmission in opposite direction is provided. Accordingly, it
is possible to utilize this receiver as a single photon receiver
for parameter adjustment. The present example embodiment will be
described below with reference to FIG. 4. In FIG. 4, the encryption
key generation unit and the optical communication unit are not
illustrated that are included in the communication device according
to the above-mentioned second example embodiment.
As illustrated in FIG. 4, the communication device A according to
the present example embodiment includes an optical switch 311 in
the output side of the transmitter 301 and an optical switch 312 in
the receiving side of the receiver 302, respectively. In addition,
the communication device A includes a parameter adjustment unit 313
that adjusts a parameter such as the transmission optical intensity
of the transmitter 301 using the detected data by the receiver 302.
The control unit 305 controls the switching operations of the
optical switches 311 and 312 and the adjustment operations of the
parameter adjustment unit 313. Similarly, the communication device
B according to the present example embodiment includes an optical
switch 412 in the output side of the transmitter 402, and an
optical switch 411 in the receiving side of the receiver 401,
respectively. In addition, the communication device B includes a
parameter adjustment unit 413 that adjusts a parameter such as the
transmission optical intensity of the transmitter 402 using the
detected data by the receiver 401. The control unit 405 controls
the switching operations of the optical switches 411 and 412 and
the adjustment operations of the parameter adjustment unit 413.
The optical switch 311 in the communication device A includes an
input port Pi, an output ports Po1 and Po2, and the optical switch
312 includes input ports Pi1, Pi2 and an output port Po. The input
port Pi of the optical switch 311 is optically connected to the
output of the transmitter 301, the output port Po1 is optically
connected to the above-mentioned quantum channel transmission
system Q1, and the output port Po2 is optically connected to the
input port Pi2 of the optical switch 312, respectively. The output
port Po of the optical switch 312 is optically connected to the
input of the receiver 302, the input port Pi1 is optically
connected to the above-mentioned quantum channel transmission
system Q2, and the input port Pi2 is optically connected to the
output port Po2 of the optical switch 311, respectively.
In a normal operation state, the control unit 305 sets the optical
switch 311 and the optical switch 312 so that the input port Pi and
the output port Po1 of the optical switch 311 may be connected, and
the input port Pi1 and the output port Po of the optical switch 312
may be connected. Consequently, the operation for the encryption
key generation is performed through the quantum channel
transmission systems Q1 and Q2, as mentioned above.
At the time of parameter adjustment, the control unit 305 sets the
optical switch 311 and the optical switch 312 so that the input
port Pi and the output port Po2 of the optical switch 311 may be
connected, and the input port Pi2 and the output port Po of the
optical switch 312 may be connected. Consequently, the weak optical
signal outputted from the transmitter 301 is inputted into the
receiver 302 through the output port Po2 of the optical switch 311,
and the input port Pi2 and the output port Po of the optical switch
312. This enables the parameter adjustment unit 313 to adjust a
parameter such as the transmission optical intensity of the
transmitter 301 using the detected data by the receiver 302. In the
communication device B, the optical switches 411 and 412, are
configured and operate as with the above; accordingly, the
description of them is omitted.
As mentioned above, according to the present example embodiment, an
optical switch is included in each communication device as optical
route switching means for turning back the transmission light from
the transmitter to the receiver in the own device. At the time of
the parameter adjustment mode, the control unit can complete the
parameter adjustment in the own device by switching the optical
switches so that the transmission light may be inputted into the
receiver in the own device; therefore, it is possible to perform
the parameter adjustment of the transmitter without damaging the
security of QKD.
In the first to third example embodiments mentioned above, a pair
of transmission system having transmission directions opposite to
each other has been illustrated, but the present invention is not
limited to these example embodiments, and a communication system
having a plurality of pairs of transmission systems may be
used.
The present invention has been described using the above-mentioned
example embodiments as exemplary examples. However, the present
invention is not limited to the above-mentioned example
embodiments. That is to say, in the present invention, various
aspects that a person skilled in the art can understand can be
applied within the scope of the present invention.
This application is based upon and claims the benefit of priority
from Japanese patent application No. 2014-170087 filed on Aug. 25,
2014, the disclosure of which is incorporated herein in its
entirety by reference.
INDUSTRIAL APPLICABILITY
The present invention is generally applicable in an information
communication system in which information transmission is performed
by a plurality of transmission systems each of which has a
predetermined transmission direction.
REFERENCE SIGNS LIST
10 First communication device 20 Second communication device 31
First transmission system 32 Second transmission system 33 First
transmission line 34 Second transmission line 101 Transmitter 102
Receiver 103 Data processor 201 Receiver 202 Transmitter 203 Data
processor 301 Transmitter 302 Receiver 303 Encryption key
generation unit 304 Optical communication unit 305 Control unit
311, 312 Optical switch 313 Parameter adjustment unit 401 Receiver
402 Transmitter 403 Encryption key generation unit 404 Optical
communication unit 405 Control unit 41, 412 Optical switch 413
Parameter adjustment unit
* * * * *